With the continuing trend toward compact electronic apparatus, there is an ever-increasing demand for miniaturized interconnection systems between the electronic components of the apparatus. An example is in computer apparatus wherein there is a constant demand to reduce the thickness or height parameters of the electronic components. With the components mounted on a printed circuit board, the thickness or height parameters relate to the distance above the board in which desired interconnections are made and which constantly are being miniaturized.
One approach to such miniaturization is to eliminate bulky electrical connector housings and, instead, to use relatively thin headers or header blocks for locating and/or inserting terminal pins into appropriate holes in the printed circuit board. The pins then are soldered to circuit traces on the board or in the holes, and a complementary connector assembly can be mounted directly to the pins projecting upwardly from the then header block.
Problems continue to be encountered in handling such header assemblies for mounting to a mounting surface of an electrical apparatus, such as positioning the header assembly on the printed circuit board. As is known, a soldering reflow vessel often is used in automatically mounting electrical connectors to printed circuit boards. It has become expedient to use a vacuum-suction nozzle for handling the electrical connector during the soldering reflow process. Specifically, an electrical connector is secured by a vacuum-suction nozzle, and the electrical connector is manipulated in position and brought to a selected position on the printed circuit board by the vacuum-suction nozzle. The electrical connector then is released from the vacuum-suction nozzle by stopping application of negative pressure thereto. After all of the desired components are mounted to the printed circuit board, gas is released inside the soldering reflow vessel or infrared rays are radiated therein until the solder applied to selected conductors on the printed circuit board has been melted, thereby soldering the selected conductors to solder tails of the electrical connector.
Such a system involving the use of a vacuum-suction nozzle is quite effective if the electrical connector has a smooth or flat top surface for securement by the vacuum-suction nozzle as described above. However, header assemblies, as described above, have the terminal pins projecting upwardly of the header block and, therefore, there is no smooth surface for direct engagement by the vacuum-suction nozzle.
Consequently, it has been proposed to employ a separate cover which presents a smooth top surface for engagement by the vacuum-suction nozzle, the cover being releasably interengaged with the header assembly. After the header assembly is brought to a selected position on the printed circuit board by the vacuum-suction nozzle, and after the soldering reflow process, the separate cover is removed and the header assembly is left interconnected to the printed circuit board by the soldering of the terminal pins to the selected conductors on the printed circuit board. This approach is shown in co-pending application, Ser. No. 07/982,210, filed on Nov. 25, 1992, which is assigned to the assignee of this invention. That disclosure shows complementary releasably retention means, such as recesses, on the side walls of the insulative header block for engagement by hook portions of cantilevered arms projecting from the separate cover. The cover has a smooth top surface for engagement by a vacuum-suction nozzle. This allows the cover to be removed from the header assembly after the soldering reflow process by disengaging the cantilevered arms. While this system has proven effective for its intended purpose, the additional releasable arms add to the overall dimensions of the interconnection area on the printed circuit board and, in essence, take up valuable "real-estate" on the board surface, at least during the manufacturing process. In other words, the cantilevered arms could interfere with electrical components positioned on the board.
The present invention is directed to an improved system similar to that disclosed in the aforesaid copending application, by providing a sliding interference-fit between the separate cover and the terminal pins totally within the bounds of the header block, the separate cover still being readily removable from the header assembly after the assembly is mounted to the printed circuit board, and with the separate cover affording a smooth surface for engagement by a vacuum-suction nozzle.